1. Field of the Invention
The present invention relates to a reel table moving device for a video cassette tape recorder, and more particularly to a reel table moving device capable of moving a reel table without using any drive motor and any sensor.
2. Description of the Prior Art
Conventional reel table moving devices are constructed to use both a large tape cassette and a small tape cassette. These tape cassettes are designated by the reference numerals 1 and 2 in FIGS. 1A and 1B, respectively. The tape cassette shown in FIG. 1A is the standard tape cassette 1 being widely used. On the other hand, the tape cassette shown in FIG. 1B is the small-size tape cassette 2.
Referring to FIG. 2, there is illustrated an example of conventional reel table moving devices. As shown in FIG. 2, the reel table moving device includes a drive motor 3 fixedly mounted to one side portion of the central part of a housing 10 and provided with a shaft 3a. To the shaft 3a, a cylindrical worm 5 is coaxially connected so that it is integral with the shaft 3a. Accordingly, the cylindrical worm 5 is operatively connected to the drive motor 3. In both sides of the cylindrical worm 5, a pair of worm wheels 4 and 4a are engaged with the cylindrical worm 5, respectively. To the worm wheels 4 and 4a, a pair of reel tables 9 are connected by means of arms 8, respectively. The arms 8 are pivotally mounted at their one ends to appropriate portions of the worm wheels 4 and 4a by means of pins 8a, respectively, and at their the other ends to appropriate portions of the reel tables 9 by means of another pins 8a, respectively.
The reel table moving device further includes a pair of guide members 6 for guiding movements of the reel tables 9, respectively. As the worm wheels 4 and 4a rotate, the reel tables 9 move laterally and vertically along the guide members 6, as indicated by arrows in FIG. 2.
Now, operation of the reel table moving device having the above-mentioned construction will be described. As a tape cassette is inserted into an inlet port (not shown) of a video cassette tape recorder, it is sensed by a sensor (not shown). The sensor senses the size of the inserted tape cassette to determine whether the inserted tape cassette corresponds to the standard tape cassette 1 or the small-size tape cassette 2. On the basis of the result of the determination, driving of the drive motor 3 is controlled. Where the inserted tape cassette corresponds to the small-size tape cassette 2, the drive motor 3 is not driven. That is, the reel table moving device operates at the state shown in FIG. 2. In the case of the standard tape cassette 1, however, the drive motor 3 is driven.
As the drive motor 3 is driven in the case of the standard tape cassette 1, the shaft 3a of the drive motor 3 rotates, thereby causing the cylindrical worm 5 to rotate. Since the worm wheels 4 and 4a are engaged with the cylindrical worm 5, they rotate in response to rotation of the cylindrical worm 5. As the worm wheels 4 and 4a rotate, the reel tables 9 connected to the worm wheels 4 and 4a by the arms 8 move downwards and outwardly along the guide members 6, respectively.
Referring to FIG. 3, there is illustrated another conventional reel table moving device. As shown in FIG. 3, the reel table moving device includes a drive motor 21 fixedly mounted to an appropriate portion of a chassis (not shown) and provided with a shaft 21a. To the shaft 21a, a cylindrical worm 22 is connected so that it is integral with the shaft 21a. In both sides of the cylindrical worm 22, a pair of worm gears 23 and a pair of worm gears 23a are engaged with the cylindrical worm 22, respectively. The worm gears 23 are connected to each other by means of a timing belt 24. In similar, the worm gears 23a are connected to each other by means of a timing belt 24a.
A pair of guide members 27 and 27a are connected to the timing belts 24 and 24a. To the guide members 27 and 27a, a pair of reel tables 25 and 25a are mounted such that they move laterally and vertically along guides 26 and 26' as the guide members 27 and 27a move, respectively.
Operation of the reel table moving device having the above-mentioned construction will now be described. As a tape cassette is inserted into an inlet port (not shown) of a video cassette tape recorder, it is sensed by a sensor (not shown). The sensor senses the size of the inserted tape cassette to determine whether the inserted tape cassette corresponds to the standard tape cassette 1 or the small-size tape cassette 2. On the basis of the result of the determination, driving of the drive motor 21 is controlled. Where the inserted tape cassette corresponds to the small-size tape cassette 2, the drive motor 21 is not driven because the reel tables 25 and 25a are positioned at their upper positions (initial positions), respectively. In the case of the standard tape cassette 1, however, the drive motor 21 is driven.
As the drive motor 21 is driven in the case of the standard tape cassette 1, the cylindrical worm 22 connected to the shaft 21a of drive motor 21 rotates. Since the worm gears 23 and 23a are engaged with the cylindrical worm 22, they rotate by the rotation of the cylindrical worm 22. As the worm gears 23 and 23a rotate, the guide members 27 and 27a move, thereby causing the reel tables 25 and 25a to move downwards and outwardly along the guide members 26 and 27a, respectively. The reel tables 25 and 25a are stopped respectively at positions allowing the standard tape cassette 1 inserted into the inlet port to be loaded.
Since the above-mentioned reel table moving devices have the sensor for sensing the size of the inserted tape cassette and drive means adapted to move the reel tables and constituted by the drive motor and worm gears or timing belts, their constructions are complex. Such a complex construction results in a complicated and expensive manufacturing procedure for constructing conventional devices.